|Plant Part and Time:||Upper mature leaves on vegetative stems prior to or at first bloom or when first squares appear.|
|Element and Sufficiency Range||Interpretation and Recommendations|
Deficiency due to inadequate N fertilization and/or ineffective N application. Poor root growth can result in N deficiency. Topdressing with 30 to 40 pounds N per acre may be sufficient to correct N deficiency. High N concentrations can result in excessive vegetative growth, making the plants more susceptible to insect injury. Follow nitrogen fertilizer recommendations to avoid both deficiencies and excesses. The nitrogen status of the crop can best be monitored through the petiole analysis program.
Less than sufficient due to low soil P level and/or inadequate P fertilization. Low soil pH or restricted root growth may reduce P uptake. Soil test and follow the soil test recommendation. No corrective treatment is recommended for the sampled crop.
Less than sufficient due to low soil K test level and/or inadequate K fertilization. Soil test and follow the soil test recommendation. No corrective treatment recommended for the sampled crop.
Less than sufficient due to very low soil pH. Deficiencies may be induced by excessive K fertilization rates. Soil test and lime to adjust the soil pH to approximately 6.0.
Less than sufficient due to low soil pH (less than 5.4) and/or low soil test Mg level. If deficiency is detected, soil apply 25 pounds Mg per acre using a soluble source of Mg, or apply a foliar application at a rate of 0.30 to 0.40 pounds Mg per acre as magnesium sulfate in 20 to 25 gallons of water. Repeated applications may be necessary during the growing season. For succeeding crops soil test and apply limestone and fertilizer based on soil test recommendation.
Less than sufficient due to low soil S level. No corrective treatment is recommended for current crop, however, for future crops a minimum of 10 pounds S per acre should be included in the fertilizer program.
Deficiency not likely to occur in most Georgia soils. High Mn concentrations indicate low soil pH. If the Mg level in the leaf tissue is less than 0.30% and the Mn level greater than 350 ppm, liming with dolomitic limestone is essential to prevent Mg deficiency and a possible Mn toxicity.
Deficiency not likely to occur. High Fe test results indicate soil or dust contamination. An accurate Fe determination can only be obtained with washed leaves.
Low B is likely to occur on near neutral, deep sandy soils low in organic matter. If low B is detected apply a foliar application of B at the rate of 0.2 pounds B per acre in 20-25 gallons of water or in the insecticide spray. Multiple applications not to exceed 0.6 pounds B per acre can be made. For subsequent cotton crops boron should be included in the fertilizer program or insecticide spray program at the rate of 1/2 pound per acre. Boron deficiency may be intensified during droughty periods.
Deficiency not likely to occur.
Deficiency may occur on near neutral, deep sandy soils low in organic matter. Soils recently limed may produce Zn deficient plants. Soil test and include Zn in the fertilizer treatment if the soil test is low and the soil pH is greater than 6.0. Deficiency symptoms will appear when the Zn level in the leaf tissue is less than 16 ppm. A foliar application of Zn will generally correct the deficiency, applying 1/2 pound Zn per acre, as zinc sulfate or 1/4 pound Zn per acre as zinc chelate.
High concentrations in the leaf tissue are primarily due to anaerobic conditions such as poor drainage or compacted soils. Acid subsoils or restricted root growth may cause high Al uptake. If both Fe and Al are high, probably due to soil and dust contamination, see Fe discussion above.